Typically, you’ll see the accuracy listed as 10m, after it comes thru the iOS Core Location APIs. The GPS chipset in the Bad Elf GPS actually provides data as precise as 2.5m, but as with any GPS receiver, this depends on your particular environment (interference, sky visibility, shielding, etc).

And what if you already have an iPhone? Doesn’t that have inbuilt GPS? Would the Bad Elf be any better?

In general, yes! The Bad Elf GPS Receiver uses the high-performance MTK3329 chipset, so it’s capable of 2.5m resolution and 10Hz reporting. It can acquire a GPS lock in places the internal GPS will not, such as inside a commercial jet flying at 565mph at 29K feet. It also supports WAAS, so you’ll see better vertical accuracy and at least 10m positional accuracy in almost all conditions. And finally, our receiver does not depend on Assisted GPS data to get a lock, so as long as you have a clear view of the sky, it will get a GPS lock within about 35 seconds.

Not convinced? Neither was I, so the kind folks at Bad Elf have given me one to play with and review. Over the next few weeks I’ll be reporting back on how well the Bad Elf works in the field for geocaching, some accuracy benchmarking with other handheld GPS units (including how well it does in an iPhone that already has GPS) and on the other fun things it allows me to do with my iPad.

From all reports, it appears the Bad Elf is proving very popular. Peter has been testing it with his wi-fi iPad and an iPhone 4, I believe, and comparing it with his beloved BB and Etrex. He’s also planning to trial it against his new Oregon 450. The results and increasing accuracy have been so encouraging that I’ve since bought my own Bad Elf to use with my iPad.